Ever wonder just how much light a polarizer filter cuts out from your photos? You can easily see the effect in the viewfinder as your turn the filter and see the reflections disappear, but what if you could take a photo of the light it cuts out?
Sounds impossible? Not if you use math… and Photoshop.
Michal Zalewski took two photos of the same scene, one with the polarizer and one without. He then put the two photos into Photoshop and subtracted one layer from the other. The result is that e can see only the differences between the two, which means that we can see the light removed by the polarizer.
Clever, and very interesting. It would be good to see how this worked on water, too, which is another of a polarizer’s best most affected subjects, but I guess it’d be impossible unless you could freeze the water.
Michal went on to play around with the picture further: once you have this polarized light separated out you can color it and use any kind of Photoshop witchcraft on it. Check out his Google+ photos to see the results.